Apparatus for reading and writing information on cards and checks is a familiar sight at many point of sale terminals and banks. An automatic teller machine (ATM), for example, is adapted to read patron identification cards. The ATM is adapted to receive the familiar plastic banking card and to read the patron identification number on the magnetic stripe which the card bears. Such machines are adapted to receive only identification cards of a particular size and thickness.
Similarly, check readers are known also. An operator of a check reader typically guides a check into a slot defined by two spaced apart rails. The rails are supported by a wear plate which acts as a bearing surface against which the edge of the check is pushed. Sensors are supported on one of the rails in a position in registry with the identification code on the check.
Most readers of this type are adapted to operate on items with a particular set of geometric characteristics. Thus, a card reader is adapted to accept only credit card-type items whereas check readers are adapted to receive the thinner, more flexible check, but not cards.
A single reader (or writing) apparatus adapted to be operative with items having a variety of thicknesses presents a variety of problems. One such problem relates to the positioning of the operating elements of the reader in a manner to accept identification media having a variety of thicknesses. This problem has been resolved by employing first and second rails in fixed, opposing positions, spaced apart a distance to accept identification media of maximum thickness. The rails are affixed to a wear plate against which the medium is pressed when it is passed between the rails. A platen is spring mounted on the first rail in a position closely spaced with respect to the second rail. Thus, the second rail and the platen form a spring loaded slot which accommodates itself to media of different thicknesses. The first rail is adapted to receive the platen when a thick medium urges the platen into its extreme position.
Further, sensing and write heads are spring mounted individually to accommodate the media of different thicknesses. The platen is apertured to permit the heads to extend through the platen to contact information on a medium. The heads are suspended by parallel spring arrangements which maintain the heads in proper alignment even though they are free to move along an axis normal to the medium to accommodate to the different media thicknesses. The multiple media apparatus of this type require that the platen be free to move to accommodate a variety of media thicknesses. Consequently, the platen has to be spaced apart from the wear plate against which the edges of the media are urged when one of such media is passed between the rails. A serious problem arises when a check is moved between the rails. The edge of the check buckles under the platen. A reduction of the separation between the platen and the wear plate to reduce the opportunity for the edge of the check to move under the platen instead cause the check to catch and tear. In the first instance, misalignment of the heads and the information on the medium occurred. In the second instance, the apparatus could not be used for checks at all.